Filters are used in a wide variety of communications circuits and applications, such as receivers, transmitters, phase-locked loops, etc. Various filters may be provided using different circuit elements including resistors, capacitors, inductors, and other elements. One example filter is a transconductor-capacitor (Gm-C) filter, which may use a combination of transconductors (Gm), capacitors (C) and resistors (R), etc. In some cases, Gm-C filters may provide lower noise and lower-power operation than some other types of filters, but may require more power in some cases. Gm-C filters may also tend to have poorly controlled passband frequency response. For example, the corner frequency and bandwidth of a Gm-C filter may vary widely due to variation of Gm and C values as semiconductor process (P), supply voltage (V) and temperature (T) vary. In addition, calibration is sometimes performed on circuits to adjust the circuits to changing conditions.